1. Work and Power
Dude! I need a raise

2. What is “Work”?
When an object actually moves in the same direction as a force.
The movement of Homer in the same
direction as the force that pushed
him means that some work
was accomplished!
Force

3. Formula for Work
Work is measured in a unit called “Joules”

4. A push or pull can always be applied, but its not until we actually move it that the person did work on the object.
Work
Whe-hew
This is FUN!
Ungh!
This is HARD WORK!
Work is when a force moves an object
If we apply a force of 100 N, but
the object doesn’t move, how
much work was done?
100 N x O m = ? W
Think: If no movement occurs,
was any work actually done?
Force
(Push)
Distance
Here’s the point: Work is what was actually accomplished!

5. Main Concept 1:
Work is only done when the force and motion are in the same direction .
The elevator is creating a force that moves the container up. The force and movement is the work that the elevator has accomplished.

6. I am here to pump you sissy's up!
What is “Power”?
I am here to pump you sissy's up!
We like to think of Power
as how strong someone is
But in science we use
“power” to say how long it
takes to do a certain
amount of work

7. Main Concept 2: Power is ONLY about how fast work gets done!
More or Less Power?
Main Concept 2: Power is ONLY about how fast work gets done!
It’s nice to get work done quickly!
So here we have a certain amount of stacked wood. We need to cut it!
We have several choices of tools we can use:
“Power Saw”
This saw will get the work
done eventually, but it takes
way too long to do it
Since this saw does the same
work faster than the hand
saw, we say it
has MORE POWER!!! OR
Hand Saw
Here’s the point:
Both will get the same work done (cutting all the boards),
but one will take less time = more power!!!

8. Power is measured in a unit called “Watts”
Formula for Power
Power is measured in a unit called “Watts”

9. Power
Gee … Isn’t he
just mighty powerful?
Ungh!
Need… more… POWER!
Once work is calculated, we simply see how much time we actually moved someone/something. Once we find our unit rate of how much work we did in 1 second, we’ve found out how much “Power” we exerted.
Force
(Push)
Time [s]
Distance

10. What is “Effort”?
While there are more technical definitions, we can think of effort as how hard it is to accomplish work.
Usually, riding on a moving object takes less
energy than walking the same distance.
So, riding on a skateboard takes less
effort to move than just walking.
Which takes LESS effort to move with:
Walking or Riding?
Effort is really the whole point of this
entire unit! Humans like things to be as easy
as possible. So we want to learn how to do work
with as little effort as possible!